1. Field of the Invention
The present invention relates to a process for the production of a laminated glass glazing constituted by several layers and having one or more wires within an intermediate thermoplastic layer and in which, prior to assembly of the layers, an electrically conductive connection is established between the wires and one or more metal elements and then the layers are joined to one another by heat and pressure.
2. Discussion of the Background
Laminated glass glazings having wires inserted in the intermediate thermoplastic layer and connected to metal elements are used, e.g. in cars, as electrically heatable glass glazings and/or as antenna windscreens. Other applications of such glazings more particularly relate to the building sector, where they can also be used as electrically heatable glazings, but also, for example, as alarm glazings for the protection of rooms against burglary and escape or as electrical protection glazings. Within the laminated glass glazing the wires are generally contacted with one or more metal elements e.g. leading to an externally accessible, electrical connection element.
When the wires in the intermediate thermoplastic layer are used as heating wires, in general several such heating wires are connected in parallel, being connected to collecting Lines arranged along two opposite edges of the glazing. The wires located in the laminated glass glazing are generally very thin, and, for example, have a diameter of 0.005 to 0.1 mm in order to bring about minimum deterioration to the transparency of the glazing. Such heating glazings are, for example, known from U.S. Pat. No. 3,895,433, DE-OS 2,127,693 and DE-OS 3,001,554.
When the wires have a metal surface, they can be visible as a result of light reflections, even in the case of small diameters. These light reflections can be particularly prejudicial when the observer and the light source are on the same side of the glazing.
In order to prevent such disturbing interference, it is known to use metal wires, which are surface-darkened. However, such surface-darkened metal wires are difficult to weld or connect in some other way to electrically conductive elements and, in addition, as the surface layers absorb light, there is a frequently encountered an undesirable increase in the contact resistance between the wires; and the metal elements.